1. Field of the Invention
The invention relates generally to the field of video telecommunications. More specifically, the invention relates to a system which permits a video caller, without human operator assistance, to access any video station of a video network through conversion of dual tone modulated frequency ("DTMF") signals or through voice recognition software, even where the video network and the remote video station have incompatible communication protocols for communicating with each other.
2. Discussion of Related Art
DATAPOINT.TM. Corporation, assignee of the present invention, currently markets a video network conferencing system identified by the designation MINX.TM.. The content of this system is incorporated herein by reference.
The MINX.TM. system is also described in U.S. Pat. Nos. 4,686,698; 4,176,585; 4,710,917; 4,847,829; and 5,014,267--all of which are also incorporated herein by reference.
U.S. Pat. No. 4,236,199, issued Aug. 17, 1993 to J. Thompson, Jr. and entitled INTERACTIVE MEDIA SYSTEM AND TELECOMPUTING METHOD USING TELEPHONE KEYPAD SIGNALLING, teaches remote access to actuate a video screen using DTMF conversion software, thereby avoiding the need for fully compatible video protocols. The content of this '199 patent is incorporated herein by reference.
U.S. Pat. No. 5,480,411, issued Jan. 30, 1996 to S. Lewis and entitled INTERACTIVE SYSTEM FOR A CLOSED CABLE NETWORK, teaches a method by which users of a video network, such as those found in hotel rooms, may gain access to remote users for interactive communications. The content of this '411 patent is also incorporated herein by reference.
None of these prior art teachings reveal how a remote user may--without human operator assistance--initiate access with any video station of a closed video network, unless the communication protocols are compatible between the remote user and the network. It would be desirable to provide such capability, and thereby eliminate the need for human operator intervention.
A conventional videoconferencing system comprises a camera, video monitor, microphone, speaker, and means to modify the associated electrical signals into a form which can be conveyed by an appropriate communications channel. The camera and microphone convert visual and aural information, respectively, into electronic signals which can be conveyed over the communication link. Likewise, at the receiving end, the electrical signals received from the communication link are converted back into visual and aural information by the video monitor and speaker, respectively. This represents a point-to-point (or "two-point") videoconferencing system.
The utility of such a system may be enhanced by providing support for "multi-way" calls, where three or more videoconferencing terminals may participate in a single call. There are two approaches to multi-way calling. In the first approach, all videoconferencing terminals at a given site attach to a local videoconferencing switch or network. The switch or network is capable of connecting local terminals in either a point-to-point configuration or in a multi-way configuration. Participants outside of the local area connect to the switch or network via a coder/decoder ("codec") that is attached to one of the switch's or network's ports. Such a switch or network includes LAN-based videoconferencing networks or frequency division multiplex ("FDM") architectures, where all terminals are on a common physical bus, so that dynamic channel switching is done to effect connections (which do not possess an identifiable physical switch).
In the second approach, all videoconferencing terminals possess a codec, and all participants in a multi-way call must place a call into a centralized device. This centralized device, typically called a multipoint control unit ("MCU"), receives the video/audio data streams from the various participants and switches or multiplexes the data streams as appropriate to establish the multi-way communication between sites.
Current MCU's typically operate in a "scheduled" mode. In this scheme, each remote participant places a call to a particular number, which represents a physical port on an MCU. By prior arrangement, those particular ports have been configured to be in a conference at the appointed time.
It is often desirable to allow the user to simply "dial-up" a multi-way conference without prior arrangement. To do this using an MCU, the user must first dial-up a call to a particular port on the MCU. The user then passes information to the MCU specifying which other MCU port he wishes to connect into the call.
Most current MCU's conform to an industry-wide set of standards which define various phases of MCU operation. These standards, specifically H.231 and H.243, describe in detail how the originating terminal, which is a codec, interacts with the MCU. Included in the H.243 standard is a defined method for the originating codec to pass "destination port" data to the MCU, enabling the user can set up a call without prior arrangement.
Unfortunately, current codecs and MCU's do not typically implement this part of the H.243 standard--i.e., the part that allows the user to set up the call. With current codecs, all connections through an MCU must typically be pre-arranged.
In the MINX.TM. system, all terminals are connected directly to a local video switch and, within the local network, users simply dial-up the terminal or terminals with whom they wish to converse. The system is easily extended to route long-distance calls through use of a local codec resource.
A problem arises when a "foreign" or remote codec has an incompatible communications protocol and calls into a codec connected to the local video switch or network. If the remote codec uses an incompatible communications protocol, then it has no means to pass a destination terminal number to the video switch or network. There is no means to determine which of the local terminals is the correct destination. In the past, this problem has been solved by passing such calls to a pre-defined terminal, designated the "operator." The operator determines the correct destination terminal, places a call to that terminal, then hangs up. This leaves the remote codec in a call with the appropriate destination terminal.
The "default operator" approach is somewhat clumsy, so an improved method for connecting foreign calls into a local video network is needed.